Getting to Ovindoli

We need to get to Ovindoli from Naples (actually Sorrento). I originally thought to take the train but someone mentioned the bus. What is a better option? How do I find a bus schedule and what stations to we take/arrive? If we take the train, it looks like it's a 5 hour ride with connections? Would we take the Avezzano or Celano stop for Ovindoli? If we take the bus, is that quicker? Thank you!